package cn.yy.cloudpay.util;

/* 
 * Copyright (C) 2008 The Android Open Source Project 
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License. 
 * You may obtain a copy of the License at 
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0 
 * 
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
 * See the License for the specific language governing permissions and 
 * limitations under the License. 
 */ 
  
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.Log; 
  
/** 
 * Schedule a countdown until a time in the future, with 
 * regular notifications on intervals along the way. 
 * 
 * Example of showing a 30 second countdown in a text field: 
 * 
 * 
 * new CountDownTimer(30000, 1000) { 
 * 
 *   public void onTick(long millisUntilFinished) { 
 *     mTextField.setText("seconds remaining: " + millisUntilFinished / 1000); 
 *   } 
 * 
 *   public void onFinish() { 
 *     mTextField.setText("done!"); 
 *   } 
 * }.start(); 
 * 
 * 
 * The calls to {@link #onTick(long)} are synchronized to this object so that 
 * one call to {@link #onTick(long)} won't ever occur before the previous 
 * callback is complete. This is only relevant when the implementation of 
 * {@link #onTick(long)} takes an amount of time to execute that is significant 
 * compared to the countdown interval. 
 */ 
public abstract class CountDownTimer { 
  
  /** 
   * Millis since epoch when alarm should stop. 
   */ 
  private final long mMillisInFuture; 
  
  /** 
   * The interval in millis that the user receives callbacks 
   */ 
  private final long mCountdownInterval; 
  
  private long mStopTimeInFuture; 
  
  /** 
   * @param millisInFuture The number of millis in the future from the call 
   *  to {@link #start()} until the countdown is done and {@link #onFinish()} 
   *  is called. 
   * @param countDownInterval The interval along the way to receive 
   *  {@link #onTick(long)} callbacks. 
   */ 
  public CountDownTimer(long millisInFuture, long countDownInterval) { 
    mMillisInFuture = millisInFuture; 
    mCountdownInterval = countDownInterval; 
  } 
  
  /** 
   * Cancel the countdown. 
   */ 
  public final void cancel() { 
    mHandler.removeMessages(MSG); 
  } 
  
  /** 
   * Start the countdown. 
   */ 
  public synchronized final CountDownTimer start() { 
    if (mMillisInFuture <= 0) { 
      onFinish(); 
      return this; 
    } 
    mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture; 
    mHandler.sendMessage(mHandler.obtainMessage(MSG)); 
    return this; 
  } 
  
  
  /** 
   * Callback fired on regular interval. 
   * @param millisUntilFinished The amount of time until finished. 
   */ 
  public abstract void onTick(long millisUntilFinished); 
  
  /** 
   * Callback fired when the time is up. 
   */
  public abstract void onFinish(); 
  
  
  private static final int MSG = 1; 
  
  
  // handles counting down 
  private Handler mHandler = new Handler() { 
  
    @Override
    public void handleMessage(Message msg) { 
  
      synchronized (CountDownTimer.this) { 
        final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime(); 
  
        if (millisLeft <= 0) { 
          onFinish(); 
        } else if (millisLeft < mCountdownInterval) { 
          // no tick, just delay until done 
          sendMessageDelayed(obtainMessage(MSG), millisLeft); 
        } else { 
          long lastTickStart = SystemClock.elapsedRealtime(); 
          onTick(millisLeft); 
  
          // take into account user's onTick taking time to execute 
          long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime(); 
  
          // special case: user's onTick took more than interval to 
          // complete, skip to next interval 
          while (delay < 0) delay += mCountdownInterval; 
  
          sendMessageDelayed(obtainMessage(MSG), delay); 
        } 
      } 
    } 
  }; 
} 
